tsk-3: Add Token support (#10)

Closes #3

Reviewed-on: phoenix/textsender-api#10
Co-authored-by: phoenix <kundeng00@pm.me>
Co-committed-by: phoenix <kundeng00@pm.me>

internal/middleware/auth.go

@@ -0,0 +1,47 @@
+package middleware
+
+import (
+	"context"
+	"net/http"
+	"strings"
+
+	"git.kundeng.us/phoenix/textsender-api/internal/services"
+)
+
+type contextKey string
+
+const (
+	UserContextKey contextKey = "user"
+)
+
+func AuthMiddleware(authService *services.JWTService) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			authHeader := r.Header.Get("Authorization")
+			if authHeader == "" {
+				http.Error(w, "Authorization header required", http.StatusUnauthorized)
+				return
+			}
+
+			// Extract token from "Bearer <token>"
+			parts := strings.Split(authHeader, " ")
+			if len(parts) != 2 || parts[0] != "Bearer" {
+				http.Error(w, "Invalid authorization header format", http.StatusUnauthorized)
+				return
+			}
+
+			token := parts[1]
+
+			// Validate token with auth service
+			user, err := authService.ValidateToken(token)
+			if err != nil {
+				http.Error(w, "Invalid token", http.StatusUnauthorized)
+				return
+			}
+
+			// Add user to context
+			ctx := context.WithValue(r.Context(), UserContextKey, user)
+			next.ServeHTTP(w, r.WithContext(ctx))
+		})
+	}
+}